Radio receiving apparatus



I May 27, 1930. E. s LODGE 1,760,506

RADIO REbEIVING APPARATUS Filed July 24. 1928 Y 2 Sheets-Sheet 1 115 1a; .150 lfvw Vbltage y 27, 1930. E. G. LODGE 1,760,506

RADIO RECEIVING APPARATUS Filed July 24. 1928 2 Sheets-Sheet 2 a) T 1. 1; o o 2 fag/we a I 0 Q '5 e W 9- AD oo o 24 \miml 2 2 2 m Patented May 27', 1930 UNITED STATES PATENT OFFICE EDMUND G. LODGE, 0F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T0 ATWATER KENT MANUFACTURING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION.

OF PENNSYLVANIA name RECEIVING APPARATUS Application filed July 24,

In accordance with my invention a ballast.

resistance of material, proportions, construction and disposition of the character hereinafter described operates to maintain roughly constant or to restrict variation within suitably narrow limits of the alternating current passed through or voltage impressed upon the tube filaments or cathode heaters notwithstanding the fact that the voltage of the alternating current source may widely vary;and the ballast resistance aforesaid makes possible the standardization of the alternating current power unit of a radio receiving set for use in connection with alternating current sources in different territories and difi'ering from each other materially as to their normal voltages.

Further in accordance'with my invention a ballast resistance has such characteristics that upon turning-on the alternating current power for a receiving set it so rapidly attains a temperature 4 and resistance effecting at least approximately usual or normal filia- ,ment and heater current and voltage conditions that the undesired effects of abnormal current and voltage conditions, which adversely affect the life and characteristic of the audion tubes, shall persist so short a time 1928. Serial No. 295,026.

thermally, by radiation and particularly by convection; more particularly the unit is mounted with the turns of wire substantially horizontal and disposed one vertically above the other. v'

Further in accordance with my invention the ballast resistor is mounted, preferably detachably, in a housing, or bracket structure constitutlng a housing or flue, upwardly through which air may pass under such con-- ditions or at such rate as to determine the temperature and therefore the resistance of the ballast resistor; and more particularly the resistor unit is mounted on a bracket or housing upon the exterior of the metal or other housing of an alternating current power unit for a radio receiving set.

Further in accordance with my invention there may be associated with the housing or bracket for the ballast unit a bi-metallic or equivalent thermostatic element which will control the amount of air passing over the resistance; and preferably the thermostatic element is so disposed that the amount or rate of flow of air is automatically decreased, thereby increasing the temperature and therefore the resistance of the ballast resistor, as the alternating current voltage impressed upon the power unit increases or is the higher.

Further in accordance with my invention the power unit to which is applied or which may include the ballast resistor is disposed within the casing or cabinet in which is housed the radio receiving set proper; and more particularly the cabinet or casing is provided with an aperture, or a combination of apertures, suitably disposed with relation to the ballast unit or its supporter housing to effect circulation of air, preferably in the localized zone within the cabinet or casing of the receiving set, to effect-suitable control of temperature or operating conditions for the ballast resistor without transferring undue quantities of heat therefrom to the receiving set proper or throughout its casing or cabinet.

K My invention resides in the features of construction, proportionment, arrangement and combination of the character hereinafter described and claimed.

For an understanding of my invention and for an illustration of one of the various forms it may take, reference is to be had to the accompanying drawings, in which:

Fig. 1 is a diagram of a typical radio receiving set, supplied with alternating current power, and utilizing a ballast resistor.

Fig. 2 comprises characteristic curves explanatory of the operation of the ballast resistor.

Fig. 3 is a horizontal section view, parts in plan, of a radio receiving set with its power unit and ballast resistor Within a'cabinet.

Fig. 4 is a vertical sectional view, parts in elevation, taken on the line 44; of Fig. 3.

Fig. 5 is a vertical sectional view, parts in elevation, taken on the line 55 of Fig. 3.

Figs. 6, 7 and 8 are respectively front elevational, top plan and side elevational views of a ballast resistor unit.

In Fig. 1 there is illustrated a typical tuned radio frequency receiving set utilizing alternating current power for filament and heater circuits, as well as for the anode circuits of the vacuum tubes.

Briefly, A represents an antenna or other absorption structure between which and earth or counter capacity E is connected a variable primary of an auto transformer T across whose terminals are effectively connected the grid and filament of the vacuum tube V, (having anode a, grid 9 and cathode f), utilized in this instance as a so-called coupling tube for preventing effect of the antenna or input system upon the first of a series of tuned circuits the rotors of whose variable tuning condensers are preferably operated in unison, in so-called single dial tuning control. The output of the tube V is coupled by the step-up radio frequency transformer T to the input of the radio frequency amplifier tube V 'whose output is similarly coupled by a step-up radio frequency transformer T to the input of the radio frequency amplifier tube V whose output is similarly coupled by step-up radio frequency transformer T with the input of the detector tube V The secondaries of the transformers T T and T are shunted by variable tuning condensers C C and C whose rotors, their grounded armatures, are or may be mechanically coupled for operation in unison from a single knob or dial for simultaneously tuning the several cascaded circuits throughout anv suitable wave length range such for example as that now current in broadcasting, nauiclv from about 200 to about 600 meters.

The primaries and secondaries of the coupling transformers T T and T are relativclv reversely poled to enhance stability or stabilization of the high frequency amplifier svstems: this stabilization may be enhanced by resistances r, 1' in the grid leads of one or more of the tubes.

In the grid lead of the detector tube V is the usual grid condenser k shunted by the usual grid leak resistance r The output circuit of the detector V is coupled by an audio frequency transformer T with the input circuit of the audio frequency amplifier tube V, whose output circuit is coupled by audio frequency transformer T with the input circuit of the power amplifier tube V in whose anode circuit is connected through the condenser k the Winding of the electromagnetic unit of' the signal translating instrument I, such as a loud speaker or the like.

shunting the primaries of the transformers T and T are variable resistances r and 9*" simultaneously variable, to' produce shunting effects upon the primaries and therefore to control the volume of the signals, including speech and music, reproduced by the instrument I.

G represents generically any source of alternating'current, for example a 60 cycle constant potential source of any suitable normal voltage, for example 115 volts, which may be the voltage of the generator itself or of a supply circuit related to the source G through transformers or a series of transformers of any suitable ratio of transformation.

The electric lamp socket 1, attachment plug or equivalent is connected to the line conductors communicating with the source G. The terminals of the socket 1 connect through the radio set switch2 with the terminals of the primary 3 of a transformer in series with which is the ballast resistance R hereinafter referred to. The transformer supplies current to the filaments f of the tubes V, V V', V and V and to the heater h which by our rent traversing it is raised to incandensence or suitably high' temperature to heat, by radiation, the equipotential cathode c of the detector tube V The filaments of the tubes V, V V and V are connected in parallel with each other across the low potential secondary 4 of the power unit transformer whose primary is 3. The heater h of the detector tube V is connected in the circuit of the low potential secondary 5 of the same transformer; and the filament f of the power amplifier V is in the circuit of the low potential secondary 6 of the same transformer.

The same transformer has the secondary winding 7 connected at about its middle to earth E and having its terminals connected to the anodes a, a of the double wave rectifier tube V whose filement f is connected in circuit with the low potential secondary 8 of the same transformer.

Associated with the secondaries 4 to 8 inclusive are suitable impedances, including resistances, condensers, and inductances constituting an alternating current power or socket .power unit including a rectifier-filter system for delivering current to the anode circuits of the various tubes, at voltages suited thereto, with adequate reduction of ripple or fluctuation, to reduce the alternating current hum to suitably low magnitude, the same unit applying current at suitable voltages to the filaments and cathode heater. Such a power unit is hereinafter indicated at U with in a casing or cabinet of the radio receiving set proper.

To cause the various tubes to operate upon desirable portions of their characteristics, and to prevent damage to or deterioration of their filaments or cathode heater it is desirable that the currents through the filaments or heater, or the voltages impressed thereon or existing across the secondaries which supply them with current, shall be maintained roughly constant or within a suitably limited range of magnitudes, notwithstanding variations in the voltage of the source G, and notwithstanding the use of a set on any one of a plurality of different alternating current sup-' ply circuits differing, within reasonable limits, among themselves as to their normal voltages. 1 4

Referring to 'Fig. "2, ordinates are magnitudes of voltage impressed upon the filament or heater of a tube; in the example illustrated the voltage across the terminals of the secondary 5, the same being the voltage impressed upon the heater h of the detector tube V It will be understood, however, that in general the characteristics about to be described refer also to the filaments of only some or all of the remainder of the tubes. Abscissae are magnitudes of line voltage, that 1s, magnltudes of the voltage existing across the terminals of the socket 1. The curve K, substantially a straight line, shows that the voltage impressed upon the heater or filament of the tube varies substantially directly proportionately to the line voltage. In the example illustrated it is assumed that the minimum voltage across the heater or filament shall be 2 volts, to procure suitable orsatisfactory oporation, and that it should not exceed 2.6 volts, which is the case for example with the UX-227 tube. 7

Assuming that the set is to operate upon a minimum line voltage at the socket 1 of say 95 volts and throughout a range between 95 and the maximum of 135 volts, the maximum of 2.6 volts across the heater or filament isv reached at about 126 volts and if the set be operated on a line voltage beyond that point the filament or heater will be damaged, too rapidly deteriorate or age, or otherwise adversely affect the operation of the tube of which it is a part.

The normal voltage of the alternating cur rent at the socket 1 may for example be assumed to be 115 Volts. It may be assumed also that that voltage may fall sometimes as low as 95 caused for example by line drop due to heavy lighting or power load, or may vary upwardly say to 135 volts.

Or it may be assumed that the normal line voltages of different alternating current circuits in different cities or different territories will vary among themselves as from a minimum of say 95 volts to a maximum of 135 volts; or for example from say 105 volts to 130 or 135 volts, the 10 volts below the lower magnitude of 105 volts representing for example the drop in the line voltage due to heavy lighting or power load on the same circuit to which the socket l is connected.

To take care of these fluctuations either above or below a suitable normal voltage lying at suitable points between for example 95 and 135 volts, or to take care of the second above mentioned case, where the normal voltages of systems in diiferent localities vary among themselves, there is utilized a voltage control ballast resistor R in series for example with the primary 8 of the power unit transformer. In this position it eifects a control of the voltages of all the secondaries 4 to 8 inclusive. It will be understood, howused in the individual secondary circuits which are to be controlled. Ordinarily, however, a single resistor R in the relative tion indicated is preferred.

By utilization of ballast resistance, however, particularly as hereinafter described, radio receiving sets may be made universal in the sense that their sockets 1 may be those of any of numerous diiferent alternating current supply circuits of different normal voltages; or they may be operated from a circuit Whose normal voltage lies, between predetermined limits, such as and 135 volts, but which voltage may vary as low as 95 or as high as 135' volts.

In either of these last mentioned cases the characteristic curve representing the relation of voltage across the heater or filament to line voltage will take a form similar to that indicated at L of which it is characteristic that throughout a voltage range from 95 to 135 volts the voltage across the heater or filament lies between the allowable limits of 2.0 and 2.6 volts. In fact in the example indicated the range of voltage impressed upon the heater or filamentlies between about 2.05 and 2.5 volts.

For purposes of the character referred to the ballast resistor R may be constructed of wire or other conductor having high positive temperature coelficient. F or this purpose wi'es of copper, iron, nickel and the like may be utilized. However nickel is preferred since both copper and iron when at high temperatures readily oxidize in air, while nickel oxidizes but slightly, if at all. For brevity herein nickel will be more particularly referred to.

The size or diameter, length, disposition and relation to other circuit factors are such that a voltage control of the character referred to is obtained.

posithe dissipation of power therein represented by the square of the current multiplied by the resistance of the unit R. In consequence of its temperature rise the relation of the voltage drop across the primary 3 to the voltage drop across the terminals of the resistance R changes, and in a sense and to an extent desirable for control of the character described.

The operation or effect of the resistance R is to change, with or for different line voltages or variation of line voltage from a predetermined normal magnitude, the relation of the drop of potential across the primary 3 to the drop of potential across'the resistance R, or the voltage across the primary 3, while actually increasing somewhat in magnitude, decreases in relation to the fall of potential across the resistance R. Otherwise stated, volta 'e drop across the unit R increases more rapidly than the voltage across the terminals of the primary 3 with increase of line volt-- age at the socket 1 and hence the voltage across the terminals of any of the secondaries 4 to 8 inclusive increases at a materially lower rate than the rate of increase of the line voltage at the socket 1. In effect the resistance R changes the voltage distribution as between the primary 3 and the other elements in circuit therewith.

A further desirable characteristic of the resistance R is that its inertia to temperature and resistance change shall be suitably small, whereby the time lag or lapse of time between occurrence of a line voltage change and attainment of corresponding desired resistance on the part of the unit It shall be suitably short. This is particularly desirable with reference to the time of closure of the set switch 2 and the attainment of proper magnitude of control resistance R for the then existing line voltage.

Before the switch 2 is closed the resistance R is cold, or at room temperature, and therefore of a magnitude below that corresponding with the line voltage. Upon closure of the switch 2 there is accordingly a surge or rush of current above normal magnitude which causes temporarily application'of an abnormally high voltage across the filaments or cathode heater. However the resistance R immediately increases in magniture and after a time, dependent upon the characteristics, proportions and arrangement and mounting of the resistance R, attains a magnitude which at. the then existing line voltage causes the voltage impressed upon the \filament or cathode heater to return within ffia desired or allowable range.

A This time lag or time element may have varous durations. It is preferred, however, that it shall be less than one-half minute, and preferably of the order of five seconds.

Referring to Figs. 6, 7 and 8, the resistance R is shown as comprising a wire, preferably nickel, wound upon or around a form, block or support S of any suitable material, preferably one of low specific heat and/or low thermal conductivity. For example'it may be moulded of any suitable composition such for example as one including asbestos with suitable other ingredients and /or binder.

The edges or sides 6, e of the block S are of curved or semi-circular contour, for example about of an inch diameter or thickness, with an extreme width of block of about 1 A inches. The conductor is wound turn after turn around the semi-circular marginal edges (2 and at these edges there may be applied any suitable cement i to retain the individual turns in fixed position with respect to each other and with respect to the form S g A set comprising six tubes V-V and a reetifier tube V, may require, at a normal line voltage of 115 volts, about 0.6 ampere. Under such circumstances the nickel wire\of the resistance R may .be No. 36, Brown and Sharpe gauge, about 55 turns, spaced 4A to the inch, and having a total resistance, cold,

at F., zero primary current, of approximately 18 ohms. The proportions, particularly as to resistance and inductance of the primary 3, cooperating with such a resistance R, will be such that ata normal line voltage of 115 volts, the resistance of the unit R is about 48 ohms, or upwards of twice its resistance cold. With a line voltage of 90 volts its resistance is about ohms and at 135 volts about 60 ohms.

A resistance so constructed, having the electrical characteristics and magnitudes aforesaid, and when suitably positioned and related, particularly in a way equivalent to that hereinafter described, has the characteristics of causing such reduced rate of increase of voltage across the primary 3 with increase of line voltage that the desired re ulation of the character above described is attained.

At a line voltage of 90 volts, when R has a resistance of about 32 ohms, a voltage drop across the primary 3 is about volts and the simultaneous drop of voltage across the resistance R is about 15 volts. At 115 volts line pressure, when R has a resistance of about 48 ohms, the voltage drop across the primary is about 87 volts and that across the resistance R about 28 volts; and when the line voltage is 135 volts, and resistance R about 60 ohms, the drop across the primary is about 98 volts and that across the resistance R about 36 volts. Of the total voltage drop across the primary 3 and resistance R. the drop across the resistance R is about 20% at 90 volts line voltage; about 32% at 115 volts line pressure; and about 39% at a line voltage of 135 volts. The characteristicsof the resistance R and its relation to the pri mary are such therefore that the percentage drop across the resistance R materially inlow time element or time lag, of the order of five to ten seconds, elapsing between closure of line switch 2 and attainment of substantially full magnitude of resistance for the then existing normal line voltage.

' For a radio set of generally the character last above referred to but having one additional radio frequency amplifying tube, reguiring a current in the primary 3 of the order of 0.7 ampere at normal line voltage of 115 volts, the nickel wire may be No. 35, Brown and Sharpe gauge, spaced 44 turns to the inch, and having a resistance cold, at 7 0 F., of about 17% ohms. Such a resistance will give substantially the same type and degree of control of filament or heater voltage and will have the same time lag, namely about five seconds.

7 of temperature, of the resistance should be restricted both by way of radiation and particularly by way of convection or conduction. For this purpose the extent of contact of the resistance conductor with its form or support, as S, should be restricted, and the material of that support should be such asto conduct'as little heat as possible away from the resistance conductor itself.

The unit is preferably utilized in a vertical position, as hereinafter indicated, with the turns of the resistance conductor substantially horizontal and one disposed vertically above the other. In this 'relationthe heat lost by a lower turn or convolution is at least in part transferred to the turn or turns above, with the result that the resistance as a whole, other influences being the same, attains a higher temperature and therefore higher re sistance, for a given magnitude of current passing therethrough.

Secured by screws, bolts, or rivets y to the form S are the terminals t, t of and for the ends of the resistance conductor R and suitable for attachment thereto by soldering of conductors extending into the power unit U. The member S is provided on its one side with the upper and lower lugs m and n adapted to rest against or engage a suitable support, which in the example illustrated is the wall at of the casing for the power unit U. @n "its opposite side it is provided with the buttons or lugs'o, 0, on lugs 0 0 adjacent its upper and lower ends and adapted to engage in apertures or depressions in and abut against the metal plate or wall member p having the integral portion g having the flange a secured as by rivets to the aforesaid wall a of the casing of the power unit U.

The structure 79, q is preferably resilient to suitable extent to clamp or hold the unit or block S in fixed but detachable relation to the unit U. In addition there may be provided the turned-back flange or wall to, integral with 2, so that there is formed a substantially closed chamber or flue, open at its upper and lower ends,'in which the unit R is disposed. p

In the example illustrated the flue, housing or clamp for the unit R is disposed upon the exterior of the casing of the power unit U, having the removable cover 00, mounted upon the bottom 3 of the casing or cabinet M in which is housed the radio set proper. The cabinet M in the example illustrated is of metal and having the removable cover 2'.

The bottom y of the cabinet M is spaced from its supporting surface by the legs or feet a, Fig. 4:; and in the bottom 3 is the port or aperture 9 adjacent the unit R. And preferab y adjacent the upper end ofthe unit It,

in the rear wall of the housing M, is the port or aperture 10. These apertures permlt' respectively ingress and egress of air into and out of the cabinet M ina region or ath more or less confined to the vicinity o the resistance unit R. Air rises through the cas .ing or clamping structure within which the unitR is held, by convection, with the afore said communication of heat from a lower turn or turns of the resistance R to those above it, assisting in maintenance of hightemperature and therefore resistance of the unit R.

Below theunit R in the example illustrated is disposed the plate of insulating material 11 through which extend a group of holes 12 through whichextend the prongs or terminals of the tube V into engagementv with suitable contact structure 13 on the under side. The plate 11 is secured to a metal bracket 14 secured at 15 to the end wall to of the casing of the power unit U.

The lower and/or upper ends of the casing or fiue formed by theplates q, p, 'w and u may be permanently open, or to fixed extent open. In the example illustrated, however, there extends more or less completely across the upper erld'of this housing or flue'a bi-metallic or thermostatic element 16 secured at 17 to the side wall g of the housing or flue. With change in temperature the member 16 changes its position with respect, to the end of the flue, thereby controlling the amount or rate of flow of air upwardly through the flue.

Preferably the disposition is such that with increasing line voltage, accompanied by an increase of the temperature and resistance of the unit R, the element 16 will move downwardly, as viewed in Fig. 5, reducing the upper end outlet of the flue or housing of the unit, thereby further increasing the tempera ture therein,.and in consequence tending further to increase the magnitude of the resistance R.

In consequence the increase of drop of voltage across the primary 3 with increase in line voltage is restrained or reduced by the increase of resistance of the unit R and additionally by the reduction of rate of flow of air over that unit or through its housing or flue.

In the example illustrated the radio set proper comprises the aforesaid transformers T, T and T Figs. 3 and 5, Whose tuning condensers C C and C have their rotors mounted in bearings upon the vertical internal panel or plate P, having the rearward- 1y extending ledge N upon which are mounted the aforesaid transformers and the plates 18 and 19 of insulating material constituting receptacles or holders for the tubes V V Upon the ledge N are supported also the audio frequency transformers T and T Between the panel P and the front wall of the cabinet M is disposed the mechanism which mechanically couples the rotors of the several tuning condensers, the same comprising the metal ribbons or bands 20 and 21 driven by the drum or pulley 22 and driving the drums or pulleys 23 and 24, said drums being secured respectively upon the rotor shafts of A the different tuning condensers. On the exterior of the cabinet is the operators knob and dial D for simultaneously tuning the several circuits. There is carried by the panel P the aforesaid volume control indicated in Fig. 3 at H and operable from the exterior by the knob 25. The operating handle of the set switch 2 indicated at 26, is operable from the exteridr of the cabinet M.

As above mentioned, either or both the upper ends of the casing or flue formed by plates g, p, 'w, and u may be permanently open to a greater or lesser extent. It is characteristic of this construction that either increase or decrease of the pitch of the turns of the resistance R increases the slope of the curve L of Fi 2, that is, results inpoorer regulation. ariation in pitch, as, of four turns per inch, for example, of the described resistance for a radio set having an additional amplifying tube, results in a noticeable change, other factors remaining the same. Similarly, either increase or decrease of the diameter of the wire, increases the slope of the curve, it being understood that the number of turns will necessarily be changed to produce the same total normal resistance value. The disposition of the thermostatic element as above described efiects a greater change in the effect of resistance R for a given change in line voltageto flatten or reduce the curve L, attaining regulation of voltage applied to the tube filaments, for example, within limits not attainable by resistance R per se.

What I claim is:

1. Radio receiving apparatus comprising a cabinet, a radio receiving set therein, a casing in said cabinet, elements of an alterlast resistor controllin the supply of power from said unit tosaid receiving set, means spaced from a Wall of said casing to form a flue in which said resistor is mounted, and thermostatic means affected by the heat evolved by said resistor for controlling the rate of flow of air through said flue. I

8. Radio receiving apparatus comprising a cabinet, a radio receiving set therein, 9. casing in said cabinet, elements of an alternating current'power unit in said casing, a ballast resistor controlling the supply of power from said unit to said receiving set, means spaced from a wall of said casing to form a flue in which said resistor is mounted, and means responsive to heat evolved by said resistor for decreasing the flow of air through said flue with increase of line voltage impressed upon said power unit.

4;. Radio receiving apparatus comprising a cabinet, a radio receiving set therein, a casing in said cabinet, elements of an alternating current power unit in said casing, a ballast resistor controlling the supply of power from said unit to said receiving set, means spaced from a wall of said casing to form a flue in which said resistor is mounted, apertures in said cabinetso related to each other and to said flue as to effecta localized air current transferring heat evolved by said resistor to-the exterior of said cabinet, and means respo-nsive to heat evolved by said resistor con- .itirolling the rate of flow of air through said 5. Radio receiving apparatus comprising a radio receiving set, an alternating current power unit therefor, a ballast resistor controlling the supply of power from said unit to said set, structure forming a flue within which said resistor is disposed, and means responsive to heat evolved by said resistor for controlling the rate of flow of air through said flue.

6. Radio receiving apparatus comprising a radio receiving set, an alternating current power unit therefor, a ballast resistor controlling the supply of power from said unit to said set, structure forming a flue within which said resistor is disposed, and means responsive to heat evolved by said resistor for decreasing the rate offlow of air through said flue in response to increase of line voltage a radio receiving set, an alternating current power unit therefor, a ballast resistor controlling the supply of power from said unit to said set, structure forming a flue within 5 which said resistor is disposed, the longitudinal extent of said flue having substantial vertical component to facilitate upward passage of air-therethrough, said resistor comprising a Winding of conductor whose turns 10 extend substantially transversely to the l0ngitudinal extent of said flue and spaced from each other longitudinally of said flue, and means responsive to heat evolved by said resistor for controlling the rate of flow of air through said flue.

EDMUND G. LODGE. 

